The present disclosure relates in general to portable media devices that can interoperate with accessories, and in particular to interoperation of a portable media device with an accessory to facilitate control of a radio frequency (RF) tuner included in the portable media device.
Generally speaking, an RF tuner is a device that is capable of selecting, or “tuning in,” radio signals at a specified frequency for conversion to another medium (e.g., audio, video, data, etc.). RF tuners are available for tuning in radio signals corresponding to various different types of broadcasts, such as radio and television (TV) broadcasts. The broadcasts can be encoded in analog or digital format. Examples of analog broadcasts include Frequency Modulation (FM) radio, Amplitude Modulation (AM) radio, and National Television Systems Committee (NTSC) TV broadcasts. Examples of digital broadcasts include HD Radio, satellite radio, Advanced Television Systems Committee (ATSC) TV, and Digital Video Broadcasting (DVB) TV broadcasts.
In recent years, there has been growing demand for the inclusion of RF tuning functionality in portable media devices. As used herein, a portable media device, or PMD, is a handheld device that is capable of storing and playing back digital media assets such as audio, video, and/or still image files. Some portable media devices, such as the iPod® and iPhone™ (both developed by Apple Inc., assignee of the present application), can provide users a variety of services in addition to media storage and playback. Examples of such services include the storage of personal data such as calendar, contacts, and notes; Internet access; mobile telephony; and the ability to selectively download and run various application programs.
Certain existing portable media devices have built-in FM tuners for tuning in analog FM radio stations. However, these built-in tuners are typically operated via an input interface located directly on the portable media device. Generally speaking, these built-in tuners cannot be controlled via separate accessory devices (also referred to herein as “accessories”) that are capable of communicating user input to the portable media device. In addition, these existing built-in tuners are not designed to tune in digital radio (e.g., HD Radio, satellite radio) or digital TV (e.g., ATSC, DVB) broadcasts.